In this work we explore the radiocarbon (14C) signal as an independent tool to assess the year of formation of individual tree rings of tropical species in northern Brazil. Three different species were analyzed in this work: Dipteryx magnifica, Enterolobium maximum, and Hymenolobium petraeum. The studied samples are from the stem of only one individual of each species, all cut down in 2008 in Porto Trombetas, Pará, Brazil. Individual tree rings were identified based on wood anatomy and they were counted from bark to pith. Several rings were selected for 14C analysis in order to cover the overall shape of the 14C atmospheric bomb peak (after 1955). The 14C content was measured at Laboratory of Radiocarbon, Universidade Federal Fluminense (LAC-UFF). Results are compared with the Southern Hemisphere 14C atmospheric calibration curves. For E. maximum and H. petraeum the 14C signal exhibits an overall good match with the SH zone 3 and suggests annual seasonality in the growth-ring formation. These species offer suitable characteristics for dendrochronology. The D. magnifica shows mismatches in the 14C measurements that are likely a result of difficulties in identifying ring boundaries with certainty. Additional techniques may be helpful to disentangle the origin of this discrepancy.

One new species and six new records of the crustose lichenized genus Graphis are reported from Thailand. Graphis koratensis Pitakpong, Kraichak & Lücking sp. nov. is characterized by lirelline ascocarps with whitish grey or grey-green pruina along the slit, transversely septate ascospores, and the presence of norstictic acid. Phylogenetic analyses with two loci (mtSSU and nuLSU) show the distinct position of this new species within the genus. Six new records for Thailand are reported, including G. cincta (Pers.) Aptroot, G. jejuensis K. H. Moon et al., G. nigrocarpa Adaw. & Makhija, G. renschiana (Müll. Arg.) Stizenb., G. seminuda Müll. Arg., and G. subserpentina Nyl.